A heat sink is a piece of metal that sits on top of a computer chip such as a CPU and draws power away from components by letting it rise through a set of fins. By themselves, heat sinks are passive; they have no moving parts. However, in most cases--especially with desktop CPUs and GPUs--the heat sink is combined with a fan that blows the hot air away or a liquid cooling solution that carries the heat away through pipes.
A heat sink needs to make strong contact with the source of heat in order to maximize cooling. Heat sinks leverage a thermal conductor to move the heat into fins, which have larger surface areas and thus disperse the heat throughout the computer. Interestingly--and logically--a heat sink is a type of radiator.
This article is part of the Tom's Hardware Glossary.
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